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Neuropediatrics 2023; 54(05): 356-358
DOI: 10.1055/a-2090-5922
Videos and Images in Neuropediatrics

Myoclonic Status Epilepticus in TBC1D24-Related Developmental/Epileptic Encephalopathy (DEE)

Ranjith Kumar Manokaran
1   Division of Neurology, Department of Paediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada
,
Jaina Patel
1   Division of Neurology, Department of Paediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada
,
Suvasini Sharma
1   Division of Neurology, Department of Paediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada
2   Neurology Division, Department of Pediatrics, Lady Harding Medical College and Kalawati Saran Children Hospital, Delhi University, New Delhi, India
,
Ayako Ochi
1   Division of Neurology, Department of Paediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada
,
Puneet Jain
1   Division of Neurology, Department of Paediatrics, University of Toronto, The Hospital for Sick Children, Toronto, Ontario, Canada
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A 12-year-old boy presented with infantile-onset drug-resistant epilepsy (generalized, focal, myoclonic seizures), global developmental delay, and cerebellar signs. He was born out of a nonconsanguineous marriage. There was no significant family or perinatal history.

Magnetic resonance imaging brain showed nonspecific cerebellar atrophy. Electroencephalography showed generalized 4 to 5 Hz spike-and-waves/polyspike-and-waves, mainly during wakefulness with photoparoxysmal responses.

He was on brivaracetam, topiramate, and clobazam for his seizures. He failed multiple antiseizure medications in the past. He presented at 9 years with myoclonic status epilepticus ([Video 1], [Fig. 1]) followed shortly by a transient movement disorder ([Video 1]). This was possibly provoked by prior addition of carbamazepine. Myoclonic status was aborted with intravenous lorazepam and carbamazepine was subsequently stopped. He continues to get weekly/monthly generalized tonic–clonic seizures.

Video 1 Part 1: Patient showing generalized myoclonic status epilepticus, aborted by intravenous lorazepam. Ongoing carbamazepine was replaced with clobazam. Part 2: One month later, he again presented with left sided hemiballismus and choreoathetoid movements, which resolved in 2 months. Concomitant electroencephalography did not show any ictal changes.


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Fig. 1 Interictal electroencephalography (EEG) showed frequent posterior dominant generalized and bilateral occipital spike/polyspike wave complexes (A): Ictal EEG showed continuous myoclonic jerk artifacts admixed with generalized spike/polyspike wave complexes (B); (sensitivity—20 µV, time base—30 mm/sec, sample rate—256 Hz).

Whole-exome-sequencing revealed a homozygous pathogenic variant in TBC1D24 gene (c.671A> G, p.Y224C).[1] [2] Both the parents were carriers of the same variant.

TBC1D24-related disorders can be clinically heterogeneous and include isolated deafness, deafness-onychodystrophy-osteodystrophy-intellectual disability syndrome, benign myoclonic epilepsy, and developmental-epileptic encephalopathy. Convulsive/nonconvulsive status epilepticus is commonly seen. Other genes reported with myoclonic/focal clonic status include POLG1, GRIA3, and DNM1L.[3] [4] Hereby, we report a rare case of genetic epilepsy complicated with myoclonic status epilepticus and a transient movement disorder.



Publication History

Received: 10 April 2023

Accepted: 05 May 2023

Accepted Manuscript online:
10 May 2023

Article published online:
18 July 2023

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  • References

  • 1 Nykamp K, Anderson M, Powers M. et al; Invitae Clinical Genomics Group. Sherloc: a comprehensive refinement of the ACMG-AMP variant classification criteria. Genet Med 2017; 19 (10) 1105-1117
    CrossrefPubMedGoogle Scholar
  • 2 Richards S, Aziz N, Bale S. et al; ACMG Laboratory Quality Assurance Committee. Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med 2015; 17 (05) 405-424
    CrossrefPubMedGoogle Scholar
  • 3 Zhang J, Chen J, Zeng Q. et al. Infantile epilepsy with multifocal myoclonus caused by TBC1D24 mutations. Seizure 2019; 69: 228-234
    CrossrefPubMedGoogle Scholar
  • 4 Balestrini S, Milh M, Castiglioni C. et al. TBC1D24 genotype-phenotype correlation: epilepsies and other neurologic features. Neurology 2016; 87 (01) 77-85
    CrossrefPubMedGoogle Scholar